Mechanisms of surface wave plasma excitation and energy transfer from electromagnetic wave.

朗缪尔探针发现了与表面波等离子体激发有关的现象。总结如下： 1．随着压力的降低，轴向密度分布变得适中。2．在压力低于 50 mTorr 时，在距离石英板 1-2 cm 处检测到的探头特性曲线上会出现下降。将探头偏置电压降低至相对于地的 -80 V 以下，下降消失。这意味着倾角是由热电子产生的，而热电子是由一定的电子加速机制产生的。3．仅一侧金属表面的探针测量表明，高能量的电子流从石英板向下飞流到放电室​​的底部。 4．对设置在距石英板 5 mm 处的偶极天线拾取的信号进行频率分析。结果，观察到三个频谱，例如D20=2.45GHz、D21=10MHz和D22=D21D2。显然D20D2是微波频率，而D21对应离子等离子体频率。因此，这些现象被认为是由所谓的“参数不稳定性”激发的。总之，参数不稳定性激发的朗缪尔波可能通过诸如朗道阻尼之类的非线性现象将能量传递给电子，然后这里产生的热电子可能有助于等离子体的产生，尽管由于填充压力低，电子与中性粒子的碰撞并不那么频繁。

Phenomena related to the surface wave plasma excitation have been found by Langmuir probe. They will be summarized as follow;1. Axial density profiles became moderate with the pressure decreasing.2. At the pressure lower than 50 mTorr, the dip appears on the probe characteristic curves detected around 1-2 cm from the quartz plate. Decreasing the probe bias voltage lower than -80 V with respect to the ground, the dip disappeared. This means that the dip is created by hot electrons which is produced by a certain electron acceleration mechanism.3. Measurement by the probe with a metal surface only on its one side showed that the electron flux with high energy flew down from quartz plate to the bottom of the discharge chamber.4. The signals picked up by dipole antenna which is set up at 5 mm from the quartz plate are frequency analyzed. As a result, three frequency spectra such as fィイD20ィエD2 = 2.45 GHz, fィイD21ィエD2 = 10 MHz and fィイD22ィエD2 = fィイD21ィエD2 + fィイD20ィエD2 are observed. Apparently fィイD20ィエD2 is the microwave frequency, while fィイD21ィエD2 corresponds to ion plasma frequency. Therefore, these phenomena is considered to be excited by so-called "parametric instability".In conclusion, Langmuir wave excited by parametric instability may transfer the energy to the electrons through a nonlinear phenomena such as Landau damping and then hot electrons produced here may contribute to the plasma production even though the electron collision with neutral particles were not so frequent because of a low filling pressure.